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Showing posts with label AC voltage. Show all posts
Showing posts with label AC voltage. Show all posts

Tuesday, September 27, 2016

Measuring AC Main Supply Voltage with Arduino (2)

   In article named Measuring AC Voltage with an AC to AC power adapter from OpenEnergyMonitor I found a interesting solution for measure AC voltage.
   Schematic is
   I use EmonLib library like in article:
   On DSO I see on R1 resistor
and at A2 input of Arduino board (on R4 resistor):
   I use an LED display with 8 digit 7-segment drived by MAX7219 (I present on article namend Modul de afisare cu 8 cifre LED din 7 segmente fiecare controlate de MAX7219
   I use some configuration for LedControl library (dosc at The Arduino LedControl library):
   Test schematic is
   I write main_voltage_emonlib_1.ino sketch and upload in Arduino board:

Measuring AC Main Supply Voltage with Arduino

   If you need to measuring AC main supply voltage with Arduino must made some calculation.
   I use a simple schematic:
   I can directly measure the DC voltage on R1 resistor. I use internal reference from Arduino Uno board (compatible board with ATmega328 microcontroller) so maximum value for U2 can be
U2 = U1*(R1+R2)/R1 = 1.1*(1+22)/1=25.3V
  AC voltage U1 so DC voltage U2 = U1*1.41-Udiode
  If we put value in equation
U1 = (U2+Udiode)/1.41
because I use trafo U0 = k * U1.
  For tests, I use a trafo imprinted 220V/2x12V 200mA but if I measeure voltage from secondary coil
I found 11V when main voltage is 220V, so k = 220/11=20. I use an 1N4007 diode and Udiode=0.65V.
  I use an LED display with 4 digit 7-segment drived by TM1637 (who I present on base blog in article named Afisaj cu 4 cifre controlate de TM1637 si Arduino and sketches are at https://github.com/tehniq3/TM1637-display):
   Schematic for display put on Arduino Uno is:
   I write main-voltage_0.ino sketch and upload in Arduino board and I made a movie named main supply voltage measured with Arduino